Means for controlling the operation in pulp grinding



y 1931. c. D. DE MERS 1,806,238

MEANS FOR CONTROLLING THE OPERATION IN PULP GRINDING Filed May 31, 1930 @(INVENTORQQa 07a, 972m BY ATTORNEY Patented May 19, 1931 UNITED STATES PATENT OFFICE CLAYTON D. DE OF NEW YORK, ASSIGNOR TO TAYLOR INSTRUMENT COMPANIES, OF ROCHESTER,

NEW YORK, A. CORPORATION OF NEW YORK MEAN S FOR CONTROLLING THE OPERATION IN PULP GRINDING Application filed Bay 31,

This invention relates to meansfor controllin the operation of pulp grinding.

s is well known, the grinding temperature or rather the temperature of the grinding stone in a pulp-grinding machine must be controlled for the reason that a scorchlng or burning of the fibre detrimentally affects the color and the life of the fibre and for the additional reason that the expansion incident to unduly high temperatures and the subsequent contraction impose such severe strains upon the stone that in many cases the stone blisters (surface shelling) or even cracks and breaks.

It is the object of the invention to provide apparatus for controlling the temperature of a grinding stone within narrow limits.

Having reference to the accompanying drawings, wherein Fig. 1 is an elevation, partly in section of a pulp-grinding arrangement embodying the invention; and

Fig. 2 is a section taken on line 22, Fig. 1, 1 represents a grindin stone mounted for rotation on a shaft 2. an each side of the stone is disposed a magazine 3 containing stacks of logs and a pressure foot 4 operated by the rod 5a of a piston 5 of a hydraulic motor 6, presses the logs at the bottom of the magazine against the stone 1. The bottom of each magazine is formed by a plate 7 which is adjustable toward the stone by means of screw threaded rods 8.

By means of a supply line 9 water is directed upon the top of'the stone 1 as a permanently operating cooling medium. In addition to this cooling medium there is provided a supply line 9a controlled by a valve 9?; for directing an additional amount of cooling water against the stone. The valve 96 is controlled by a temperature-responsive mechanism, which will be more fully described.

Below the stone is provided a pan 10 which discharges into a trough or launder 11.

The apparatus thus far described constitutes part of the prior art.

The invention. consists in the of a temperature bulb 12 close to of disposition the surface the stone and close to but above the plane 1980. Serial No. 458,030.

where the surface of the stone emerges from the water in the pan 10. The bulb 12 preferably extends from one end of the stone to the other and is mounted on the toe plate 7 close to the front edge thereof. By means of the capillary 13, the bulb 12 is connected with an apparatus 14. for controlling the flow of compressed air from a supply line 15 to the diaphragm 90 actuating valve 96.

The operation is as follows:

The bulb 12 is disposed above the level of the water in the pan 10, but close to the surface of the stone. As the stone leaves the water, the pulp and liquid carried with it are thrown off tangentially against the bulb 12. I have found that the temperature of the particles thrown off at this point in the travel of the stone is more reliably indicative of the true temperature of the stonethan any other criterion. It is, of course, practically impossible to have the bulb in actual contact with the stone. The liquid in the pan, I have found, has neither the temperature of the stone, nor a temperature which may be considered as a reliable measure of the temperature of the stone. The intermittent supply of cooling water from the line 9a variably depresses the temperature of the liquid and the bulb below the true temperature of the stone and the limits of variation are distinct.- ly too wide to afford a reliable measure of the temperature of the stone. Evidently the particles thrown oif tangentially from the stone remain in contact with the stone alone in the form of a surface film, although for only a short time, and during this surface film contact the particles are heated up to a temperature above the temperature of the liquid in the pan and the temperatures of the particles when they strike the bulb probably represent a curve which is substantially parallel to the curve of the true stone temperature and closely follows all fluctuations.

In addition to the temperature effects from the stream of particles thrown oif from the stone, the bulb, of course, also receives heat from the stone due to its position in close proximity to the stone.

Since the bulb is mounted on the adjustable 'toe plate 7 which is adjusted from time to 2' a v a v 1-,soe,aaa"- time to follow the wearing stone, the distance of the bulb from the stone remains substantially constant.

I claim:

1'; In a pulp grinder, the combination with a grindin stone, means for forcing the material to e ground into contact with the stone, means for applying a cooling hquid to the stone, including a receptacle below the stone for maintaining the cooling liquid in flowing contact with the lower portion of the stone and a temperature-sensitive bulb disposed above the level of the liquid in the rece tacle in the path of the liquid thrown ofi rom the rotating stone and means controlled b the bulb for controlling the application 0 the cooling liquid to the stone.

2. An apparatus according to claim 1,

wherein the ulb is coextensive in length with the length of the grinding stone.

3. An apparatus according to claim 1, wherein means are provided for adjusting the bulb toward the grinding surface of the stone.

4. In a pulp grinder, the combination with a grinding stone, means for forcing the material to be ground into contact with the stone, means for applying a coolin liquid to the stone including a receptacle. low the stone for maintaining the cooling liquid in flowing contact with the lower portion of the stone and ;a temperature-sensitive bulb disposed in close proximity to the surface of thestone, above the level of the liquid in the recriiptacle and in the path of the liquid thrown o from the rotating stone, means for adjusting the position of the bulb relatively to the grinding surface of the stone and means controlled by the bulb for controlling the application of the cooling liquid to the stone.

In testimony whereof I aflix m si ature.

CLAYTON D. D RS. 

